Hi, my 2011 Fiesta 1.6 TDCi keeps popping up a P0299 turbo underboost fault at exactly 67mph? Under normal driving conditions its perfectly fine, this only seems to happen at motorway speeds. Any ideas before I start replacing MAP/MAF sensor etc? Just wondering if someone has had this before, as all seems fine untiul that speed. The turbo seems to function fine so guessing something simple?

Thanks.

On 10/22/2024 at 2:54 PM, Oscar Jr said:

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My sons citroen with the same engine had the same problem..turned out it was the turbo pressure valve was not boosting properly..we bought a non original one from ebay that didn't work so got one from the breakers  for £15 

Faulty was getting was lack of power and no turbo boost and black smoke on heavy acceleration. 

 

14 hours ago, Danny cj said:

My sons citroen with the same engine had the same problem..turned out it was the turbo pressure valve was not boosting properly..we bought a non original one from ebay that didn't work so got one from the breakers  for £15 

Faulty was getting was lack of power and no turbo boost and black smoke on heavy acceleration. 

 

Thanks for the reply. Oddly enough I changed the turbo pressure valve a while ago, got one off ebay, and it didnt solve the problem. I may try buying a genuine second hand one.

No black smoke from mine. Eevery now and again I get white smoke.

When you start the car look at the turbo actuator..it should move when started..ours didn't it was stationary..

Took 20 mins to change and test.

2 bolts and 3 pipes..remember the position of each pipe..